Techniques are conventionally available for objectively and quantitatively evaluating a cardiac function by obtaining motion information, such as displacements and distortion of a tissue, of the heart. For example, a technique for ultrasound diagnostic imaging is available in which the motion of the heart is estimated by chronologically collecting ultrasound images of the heart, performing pattern matching of local regions on the ultrasound images, and tracking the local regions.
In the case of dealing with a two-dimensional medical image, a boundary of region of interest (ROI) is easily adjusted by user control on the image displayed on a monitor. For example, the direction and distance of movement of the boundary of region in the plane of a screen are associated in advance with an operation (such as a drag-and-drop operation) of an input device so that the boundary of the region of interest is adjusted by only control of the input device in the case in which an ultrasound image of a heart muscle is displayed in a divided manner in a plurality of regions in a cross-section of the heart.